One-Step Synthesis and Optical and Electrical Properties of Thin Film Cu3BiS3 for Use as a Solar Absorber in Photovoltaic Devices

We have synthesized Cu3BiS3 thin films on fused silica substrates in a one-step process by reactive sputter deposition of Cu−S and Bi on hot substrates. This one-step process produces films that are crystalline, phase-pure, dense, smooth, and continuous. As-deposited films have a direct forbidden band gap of 1.4 eV, an optical absorption coefficient of 1 × 105 cm-1 at 1.9 eV, p-type conductivity, and an electrical resistivity of 84 Ω·cm. Postdeposition annealing in an H2S atmosphere increases crystallite size and reduces electrical resistivity of films to 9.6 Ω cm.